Born in Jasper in 1913 to parents Edwin and Margaret, Cottam later became a member of the Royal Canadian Air Force and joined the war effort.
He was hand-picked by 24-year-old squadron leader and accomplished flier Guy Gibson, who was instructed to compile a crew for a top-secret operation.
“They were all picked from the same group of bomber squadrons and in some cases, Gibson knew some of them,” said Dave Birrell, director of library/archives/displays at the Bomber Command Museum of Canada in Nanton, Alta. “[Cottam] would have come with his crew, which was [under] squadron leader Henry Maudsley.”
The squadron didn’t know yet, but their mission was to breach Germany’s Mohne, Eder and Sorpe dams—a tough task that involved low flying.
Aircraft designer Barnes Wallis conceived the raid and devised a 9,500-pound weapon meant to be dropped at a low level while rotating backwards at 500 rpm. “I’ve seen one,” said Birrell of the weapon. “[It’s] very thick, heavy steel and filled with explosives.”
If released 411 metres from the dam, at a height of 60 feet while traveling 370 kilometers per hour, the weapon would skip along the water and hit the dam.
“Once it struck the dam it worked its way down the dam wall and when it reached a certain depth, there was a sensor in it that exploded it.”
The squadron trained eight weeks before the big mission on the night of May 16. “It was all done in a very short period of time because it could only be done in the full moon and they had to do it when the reservoirs were full of water for it to work.”
Practicing low-level flying was key, said Birrell. “They wanted to avoid radar, which was pretty primitive at the time, but still somewhat effective, and also they wanted to not be seen by fighters.”
The squadron flew Lancasters, the only airplanes capable of dropping such a weapon. Each Lancaster housed seven or eight crew members.
After only eight weeks of training, by the light of the moon, the Dambusters launched their raid.
Detailed accounts of that raid have been published by the Bomber Command Museum of Canada. Included are memories like this one: “We were flying so low that more than once Spam (bomb aimer Fred Spafford) yelled at me to pull up quickly to avoid high-tension wires and tall trees,” squadron leader Gibson said after the mission.
When Maudsley’s crew, including wireless (radio) operator Cottam, arrived in Germany, the first dam (Mohne) was already breached.
“Our load sent up water and mud to a height of 1,000 feet. The spout of water was silhouetted against the moon,” recalled pilot David Maltby. “It rose with tremendous speed and then gently fell back.”
Maudsley’s plane was one of three Lancasters to attack the second dam, said Birrell.
“Something went wrong, they didn’t break the dam, but the third airplane that went in did break the second dam.”
En route home after dropping their weapon, Maudsley’s plane was shot down by anti-aircraft fire near the Dutch border.
Cottam was laid to rest in Germany’s Reichswald Forest War Cemetery.
Of the 133 airmen that participated in the Dams Raid, 77 returned to the air base. An additional three became prisoners of war. Fifteen of the 30 Canadian Dambusters died during the mission.
The third dam (Sorpe) wasn’t destroyed, but the Dams Raid was deemed a success and a morale booster for the Allies.
Britain and Canada had been at war for almost four years, explained Birrell. The Nazis occupied France, Belgium, The Netherlands and all of northwestern Europe, but “the UK was hanging in there.
“So all of a sudden when this happened, there was something to cheer about, something to celebrate,” he said. “We were able to go right into Germany and break these dams with a spectacular raid by all these brave airmen. So the newspapers really played it up.”
Water and power supplies were disrupted and a total of 70,000 people were diverted from their wartime duties to fix roads, railways and bridges.
In honour of the Dambusters’ 70th anniversary, the Bomber Command Museum of Canada is hosting an all-day event on May 11. Along with commemorative services, “we’ll be running our Lancaster bomber in honour of the Canadian Dambusters,” said Birrell.
Included in the exhibit is a piece of Cottam’s history. “His logbook was donated to our museum at some point, it’s pretty special to have … it’s interesting this young guy from Jasper ending up in that raid.”
More information about the museum and the Dams Raid is available at .
